Ultrasensitive NH3 Gas Sensor Based on Au/ZnO/n-Si Heterojunction Schottky Diode

An ultrasensitive ammonia gas sensor based on Au/ZnO/n-Si heterojunction Schottky diode has been fabricated by using sputtering system and photolithography. Device properties such as structural, morphological, optical, and electrical were analyzed and reported. Based on material parameters, the correlation between the optical and structural properties with gas sensing behavior has been discussed. The best sensing performance has been obtained for 150 °C operating temperature. For 10- and 50-ppm NH ₃ gas concentration, we have found sensor response 39.2(%) and 75(%) with 23/43 and 18/53 s response/recovery time. The I-V characteristics with device parameters of the diode have been investigated in the different period/interval of time (20 months) and found that the proposed Schottky diode has excellent stability thus can be utilized as gas sensing electronic devices. A correlation between the stability and performance of the proposed device with electrical properties has also been established.